1. Field of Invention
The field of the currently claimed embodiments of this invention relates to systems and methods of detecting retained foreign bodies, and more particularly systems and methods of detecting foreign bodies retained in a patient during or after surgery.
2. Discussion of Related Art
Objects used during surgery can be unintentionally left in the patient. Such a retained foreign body (RFB) in which an object is left in a patient after surgery is a rare event. The incidence rates of RFBs are reported in the range of 1 RFB per 5500 operations for RFBs detected peri operatively and 1 RFB per 9000 operations to 1 per 19,000 for RFBs detected postoperatively. Though rare, RFBs can cause a number of serious complications, such as prolonged operating time, abscess formation, and death.
The consequences of failing to detect RFBs have been well studied, as is described in the following examples:                Cima R R, Kollengode A, Garnatz J, et al. Incidence and characteristics of potential and actual retained foreign object events in surgical patients. J Am Coll Surg 2008; 207:80-87.        Gawande A A, Studdert D M, Orav E J, et al. Risk factors for retained instruments and sponges after surgery. N Engl J Med 2003; 348:229-235.        Kaiser C W, Friedman S, Spurling K, Pfeifer R. The retained surgical sponge. Ann Surg 1996; 224:79-84.        Gibbs V C, Coakley F D, Reines H D. Preventable errors in the operating room: retained foreign bodies after surgery—Part I. Curr Probl Surg 2007; 44:281-337.        
However, the process of detecting RFBs has not been adequately studied. The process of detection includes factors contributing to the decision to prolong the search for RFBs, the labor (or steps) expended to search for RFBs, and the time it takes to look for RFBs.
Nonetheless, due to the serious consequences and liability issues, the search for RFBs has an impact on each and every surgery performed. Consequently, the process of detection is arguably larger in scope today than in the past due to having to detect rare occurrences in a high volume of data. Current proposed and prior art technologies include automated data identity capture (ADIC) methods (e.g. bar codes and RFID tags). However, such prior art can only be used to detect sponges. Further, they do not decrease the need for x-rays because in 81% of cases, x-rays are taken to identify RFBs independent of sponge count results. In other words even if one uses ADIC technology one would still have to take an x-ray in 81% of cases as such using ADIC technology would not only prolong the process of looking for RFBs but would also necessitate an X-ray because not all RFB are detected with ADIC technology. Further ADIC does not address the problem of only a part of an instrument being lost as of now such parts can only been seen with X-ray. Therefore, such approaches are not widely accepted and currently manual counting and x-ray methods are the standard of care. However, the standard of care has its limitations as well: up to 20% of positive x-rays are read as falsely negative and the accuracy of radiologists' determination of RFBs decreases as the size of the RFB decreases so that RFBs less than 10 mm in length have an only 30% chance of being detected by radiologists. There thus remains a need for improved methods and systems for detecting RFBs.